1. Field of the Invention
The present invention relates to a pump, driven by water under pressure, for pumping viscous fluids.
2. Description of the Prior Art
Pumps used for pumping fluids are most commonly powered by electric or internal combustion engines. In many circumstances it may be very inconvenient to provide electrical power or an auxiliary engine to drive a pump. As an example, in the fire fighting field it is often times desirable to have an auxiliary pump for delivering fluids, such as fire retardant foams, to the high pressure hoses or nozzles used for extinguishing fires. The auxiliary pump used for pumping fire retardant foams usually are powered by electric motors or small internal combustion (IC) engines. When using the electrically powered pumps in areas where electricity is not available, auxiliary generators must also be carried in the fire engine. The electric motor and its associated generator, or the IC engine are heavy and cumbersome and take up valuable storage space in the fire engine. It would be possible to modify the fire engine and add a fire retardant foam pump that runs off the engine of the fire engine in the same manner as the pumps that supply water to the fire hoses. However, this approach would necessitate expensive modifications to the fire engine, and would be very difficult in older fire engines. Therefore, a need exists in the art for a fire retardant foam pump that can be driven by, for example, water supplied by one of the fire engines own high pressure water hoses.
It should be borne in mind that the fire fighting field is mentioned only as one example of a field where the present invention may be applied. The pump of the present invention is generally applicable to any situation where an inexpensive means is needed to pump a fluid and a plentiful supply of another fluid under pressure is readily available.
Hydraulically driven reversing pistons have been proposed in the prior art. However, none of the prior art teach or suggest the valve actuation mechanisms of the present invention.
U.S. Pat. No. 2,041,394, issued to Mark K. Belcher on May 19, 1936, shows a fire extinguisher and blowout preventer for oil wells. Belcher shows a piston and cylinder arrangement designed for using steam pressure to eject fire extinguishing chemicals from the cylinder in the event of a well blowout. The Belcher piston is not configured for reciprocating operation, and all the valves to the cylinder are manually operated.
U.S. Pat. No. 4,174,928, issued to Richard D. Austin on Nov. 20, 1979, shows a reciprocating concrete pump driven by a hydraulic actuator. The hydraulic actuator is a cylinder housing a reversing piston. At each end of the cylinder is and inlet for high pressure hydraulic fluid. A reversing valve switches high pressure hydraulic fluid supply from one inlet to the other at the end of each piston stroke. The piston of Austin is tapered to allow hydraulic fluid to "get behind the piston to start the return stroke". The hydraulic actuator of Austin has no provision for periodically connecting any of the inlets to an outlet for the hydraulic fluid ahead of the piston.
U.S. Pat. No. 4,627,794, issued to Ethan A. Silva on Dec. 9, 1986, shows a fluid pressure intensifier having a fixed piston positioned between two moving pistons housed within a cylinder. The valves of the Silva device are hydraulically operated rather than mechanically operated, thus Silva lacks the valve actuation mechanism of the present invention.
U.S. Pat. No. 4,761,118, issued to Franco Zanarini on Aug. 2, 1988, shows a hydraulically driven compressor that uses reciprocating pistons housed in respective cylinders. Zanarini does not teach or suggest the valve actuation mechanism of the present invention.
U.S. Pat. No. 5,094,596, issued to Larry R. Erwin et al. on Mar. 10, 1992, shows a pneumatically driven reciprocating pump. Erwin et al. do not teach or suggest the valve actuation mechanism of the present invention.
U.S. Pat. No. 5,324,175, issued to Harold P. Sorensen et al. on Jun. 28, 1994, shows a pneumatically driven compressor using a shuttle valve to switch pneumatic pressure between different sides of the driving or power piston. Sorensen et al. do not teach or suggest the valve actuation mechanism of the present invention.
U.S. Pat. No. 5,394,693, issued to Walter J. Plyter on Mar. 7, 1995, shows a pneumatically driven hydraulic pump which uses a sensor actuated switching valve to switch pneumatic pressure between different sides of the driving or power piston. Plyter does not teach or suggest the valve actuation mechanism of the present invention.
United Kingdom Patent Document Number 2 159 890 A, by Karl Bittel et al. published on Dec. 11, 1985, shows a double acting pressure intensifier which uses a fluid driven control spool. Bittel et al. do not teach or suggest the valve actuation mechanism of the present invention.
PCT Patent Document Number WO 84/02557, by Ethan A. Silva published on Jul. 5, 1984, shows a fluid pressure intensifier having a fixed piston positioned between two moving pistons housed within a cylinder. The valves of the Silva device are hydraulically operated rather than mechanically operated, thus Silva lacks the valve actuation mechanism of the present invention.
The product brochure by the Rosenbauer company describes the DELTAMATIC.TM. pumping system which incorporates a reciprocating piston pump. The brochure does not show the valve actuating mechanism of the present invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.